Optical tracking system and tracking method using the same

ABSTRACT

An optical tracking system and a method using the same capable of detecting an exact spatial position and a direction of a target regardless of the distance from the target to be calculated is disclosed. The optical tracking system and a method using the same according to an embodiment of the present invention has an effect of expanding an available area by detecting an exact spatial position and a direction of a target regardless of the distance from the target to be calculated, as well as, a system downsizing is also achieved by significantly reducing size of the marker unit compared with conventional system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/391,447, filed Oct. 9, 2014 (now pending), thedisclosure of which is herein incorporated by reference in its entirety.The U.S. patent application Ser. No. 14/391,447 is a national entry ofInternational Application No. PCT/KR2014/003782, filed on Apr. 29, 2014,which claims priority to Korean Application Nos. 10-2013-0047984,10-2013-0060034, and 10-2013-0060035 filed on Apr. 30, 2013, May 28,2013, and May 28, 2013, respectively, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

Exemplary embodiments of the present invention relate to an opticaltracking system and tracking method using the same. More particularly,exemplary embodiments of the present invention relate to a trackingsystem and tracking method using the same for surgery capable ofdetecting a spatial and direction information of a target by trackingcoordinates of markers attached on the target, in which the target aremarkers attached on a patient or surgical instrument.

BACKGROUND ART

Recently, a robot surgery have been studied and introduced to reduce thepain of patients and to recover faster in an endoscopic surgery or anotolaryngology surgery (ENT surgery).

In such a robot surgery, in order to minimize a risk of the surgery andto operate the surgery more precisely, a navigation system is used tonavigate to an exact lesion of a patient by tracking and detecting aspatial position and direction of a target such as lesion portion orsurgical instrument.

The navigation system described above includes a tracking system whichis capable of tracking and detecting a spatial position and direction ofa target such as lesion or surgical instrument.

The tracking system described above includes a plurality of markersattached on a lesion or a surgical instrument, a first and second imageforming units to form images of lights provided by the markers, and aprocessor calculating a 3-dimensional coordinates of the markers whichare coupled to the first and second image forming units and calculatinga spatial position and a direction of the target by comparing pre-storedinformation of straight lines connecting the markers adjacent to eachother and angle information formed by a pair of straight lines adjacentto each other with the 3-dimensional coordinates of the markers.

A conventional tracking system and method as described above usesdiameters of a circle of the markers formed on the image forming unit tocalculate separated distances between the markers through the processor.But, a border of circle of the marker is opaque by a distortion of alens of the image forming unit, it is difficult to calculate exactly thediameters of the circle of the markers, as well as, exact positions ofthe markers since a change of diameters of the markers are slight andhard to distinguish.

DISCLOSURE Technical Problem

Therefore, the technical problem of the present invention is to providean optical tracking system and method using the same capable ofdetecting an exact spatial position and a direction of a targetregardless of the distance from the target to be calculated.

Technical Solution

In one embodiment of the present invention, an optical tracking systemincludes at least one marker unit which is attached on a target andemits a parallel light to form an enlarged image of a pattern portion,in which the pattern portion is included inside the marker unit, animage forming unit which receives the parallel light of the patternportion provided by the marker unit and forms the enlarged image of thepattern portion, and a processor which calculates a spatial position anda direction of the marker unit by using the enlarged image of thepattern portion formed on the image forming unit.

In one embodiment, the marker unit may include at least one patternportion on which plurality of patterns are formed, at least one lightsource irradiating light toward the pattern portion, and at least firstlens portion passing a parallel light to the image forming unit in whichthe light is emitted from the light source and has passed or isreflected by the pattern portion.

Herein, it may be preferable to arrange the pattern portion at a focallength of the first lens portion.

Meanwhile, the first lens portion may be an objective lens.

In one embodiment, the light source may be arranged inside the markerunit.

Alternatively, the light source may be arranged outside the marker unit.

Herein, the light source may be an LED (Light Emitting Diode).

In one embodiment, the image forming unit may be a camera which receivesthe parallel light of the pattern portion through the lens portion whichis provided by the marker unit and forms an enlarged image of thepattern portion on a sensor portion.

Meanwhile, the processor may calculate a spatial position of the markerunit by using a position and a size change of the enlarged image ofpattern portion formed on the image forming unit, and a direction of themarker unit by using positions of the pattern portion and a size changeof the pattern portion for each area of the enlarged image of thepattern portion.

In one embodiment, the processor may calculate a spatial position of themarker unit by comparing a position and size of the enlarged image ofthe pattern portion formed on the image forming unit with a pre-storedreference position and a pre-stored reference size of the image of thepattern portion, and calculate a direction of the marker unit bycomparing a position of the pattern and a pattern size for each area ofthe enlarged image of the pattern portion with a pre-stored referencepattern position and pre-stored pattern size for each area of theenlarged pattern portion.

Meanwhile, the marker unit may reflect and release light, which isirradiated from at least one light source, in a parallel light formthrough a ball lens in which a pattern portion is formed on a surface.Herein, the pattern portion may be wholly or partially formed on thesurface of the ball lens.

In another embodiment, the marker unit may pass and release light, whichis irradiated from at least one light source and is reflected by or havepassed the pattern portion, in parallel light form through a fisheyelens.

The pattern portion may be arranged at a focal length of the fisheyelens.

Also, the light source may be arranged outside the marker unit such thatthe light is reflected by the pattern portion and passes the fisheyelens. Alternatively, the light source may be arranged in the inside themarker unit such that the light irradiated from the light sources passesthrough the pattern portion and passes the fisheye lens.

In another embodiment, the marker unit may pass and release the light,which is emitted from the at least one light source, and is reflected bythe pattern portion or have passed the pattern portion, in parallellight form through an objective lens, and releases the parallel lightthrough a prism to have different angle of views.

The pattern portion may be arranged at a focal length of the objectivelens.

Or, the light source may be arranged outside the marker unit to suchthat the light is reflected by the pattern portion and passes theobjective lens. Alternatively, the light source may be arranged insidethe marker unit such that the light irradiated from the light sourcepasses through the pattern portion and passes the objective lens.

In another embodiment, the marker unit may reflect and release thelight, which is irradiated from at least one light source, in parallellight form through a mirror portion on which a pattern portion isformed.

The marker unit may further include a first lens arranged at an intervalfrom the mirror portion to change and release the parallel light, whichis reflected by the mirror portion, once more in a parallel light form.

Also, the marker unit may further include an aperture installed on themirror portion to adjust an angle of view and a resolution of theenlarged image of the pattern portion formed on the image forming unitby adjusting a light quantity of the light flowed in to the mirrorportion.

Meanwhile, the mirror portion is a mirror with a spherical ornon-spherical shape.

Next, a method of tracking using an optical tracking system according toan embodiment of the present invention includes steps of emitting aparallel light from a marker unit attached on a target to enlarge animage of a pattern portion, receiving the parallel light provided by themarker unit and forming an image of the enlarged image of the patternportion on an image forming unit, and calculating a spatial position anda direction of the marker unit through a processor by using the enlargedimage of the pattern portion formed on the image forming unit.

In one embodiment, calculating a spatial position and a direction of themarker unit may include steps of calculating a direction of the markerunit by calculating a rotated angle of the marker unit through theprocessor by using the enlarged image of the pattern portion formed onthe image forming unit, and calculating a spatial position of the markerthrough the processor by using the enlarged image of the pattern portionformed on the image forming unit and the rotated angle of the markerunit.

Herein, calculating the direction of the marker unit may include stepsof measuring a position and a size change of the pattern portion foreach area of the enlarged image of the pattern portion formed on theimage forming unit through the processor, and calculating the rotatedangle of the marker unit by comparing a position of a reference patternportion and a size of the reference pattern portion, which arepre-stored in the processor, with the position and the size change ofthe pattern portion for each area of the enlarged image of the patternportion formed on the image forming unit.

And, calculating the spatial position of the marker unit may includesteps of measuring a position and a size of the enlarged pattern portionformed on the image forming unit through the processor, and calculatingthe spatial position of the marker unit by comparing a referenceposition and a reference size of the image of the pattern portion whichare pre-stored in the processor.

In one embodiment, the marker unit may reflect and release the light,which is irradiated from at least one light source, in parallel lightform through a ball lens in which a pattern portion is formed on asurface of the ball lens.

In another embodiment, the marker unit may pass and release the light,which is irradiated from at least one light source and is reflected byor has passed the pattern portion, in parallel light form through afisheye lens.

In another embodiment, the marker unit may pass and release the light,which is emitted to from the at least one light source and is reflectedby or have passed the pattern portion, in parallel light form through anobjective lens, and releases the parallel light through a prism to havedifferent angle of views.

In another embodiment, the marker unit may reflect and release thelight, which is irradiated from at least one light source, in parallellight form through a mirror portion on which a pattern portion isformed.

Advantageous Effects

Thus, an optical tracking system and a method using the same accordingto an embodiment of the present invention calculates a spatial positionof a marker unit by using an enlarged image of a pattern portion whichis formed on an image forming unit by emitting a parallel light from themarker unit to a pattern portion. In other words, the spatial positionand the direction of the target to be calculated are calculated withoutreduction of accuracy by enlarging the image of the pattern portion andforming the enlarged image on the image forming unit, and therefore, anaccuracy of the position of the marker unit is not dependent on aresolving power.

Therefore, an optical tracking system and a method using the sameaccording to an embodiment of the present invention has an effect ofexpanding an available area by detecting an exact spatial position and adirection of a target regardless of the distance from the target to becalculated, as well as, a system downsizing is also achieved comparedwith conventional system.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a tracking system according to a firstembodiment of the present invention;

FIG. 2 is an example drawing of a pattern portion of a marker unit;

FIG. 3 is a flow chart explaining a method of tracking a target using anoptical tracking system according to a first embodiment;

FIG. 4 is a drawing explaining a process of emitting light from a markerunit;

FIG. 5 is a drawing explaining a process of a parallel light beingincident on an image forming unit;

FIG. 6 is a flow chart explaining a method of calculating a direction ofa target using an optical tracking system of the first embodiment;

FIGS. 7a-7d are drawings explaining a method of calculating a spatialposition of a target using an optical tracking system according to afirst embodiment;

FIG. 8 is a flow chart explaining a process of calculating of a spatialposition and a direction of a marker unit;

FIG. 9 is a flow chart explaining a process of calculating of adirection of a marker unit;

FIG. 10 is a flow chart explaining a process of calculating a spatialposition of a marker unit;

FIG. 11 is a schematic diagram of a tracking system according to asecond embodiment of the present invention;

FIG. 12 is a drawing explaining a process of calculating a spatialposition of a maker unit according to a second embodiment of the presentinvention;

FIG. 13 is a schematic diagram of an optical tracking system accordingto a third embodiment of the present invention;

FIG. 14 is a drawing explaining a process of calculating a spatialposition of a marker unit according to the third embodiment of thepresent invention;

FIG. 15 is a schematic diagram of an optical tracking system accordingto a fourth embodiment of the present invention;

FIG. 16 is a drawing explaining a process of calculating a spatialposition of a marker unit according to the fourth embodiment of thepresent invention;

FIG. 17 is a schematic diagram of an optical tracking system accordingto a fifth embodiment of the present invention;

FIG. 18 is a drawing showing a marker unit according to the fifthembodiment of the present invention;

FIG. 19 is a flow chart explaining a method of tracking a target usingan optical tracking system according to the fifth embodiment;

FIG. 20 is a flow chart explaining a process of calculating a spatialposition and a direction of a marker unit;

FIG. 21 is a flow chart explaining a process of calculating a directionof a marker unit;

FIG. 22 is a drawing explaining a process of calculating a direction ofa target using an optical tracking system of the fifth embodiment;

FIG. 23 is a flowchart explaining a process of calculating a spatialposition of a marker unit;

FIGS. 24a-24d are drawings explaining a process of calculating a spatialposition of a marker unit;

FIG. 25 is a schematic diagram of an optical tracking system accordingto a sixth embodiment of the present invention;

FIG. 26 is a schematic diagram of an optical tracking system accordingto a seventh embodiment of the present invention;

FIG. 27 is a schematic diagram of an optical tracking system accordingto an eighth embodiment of the present invention;

FIG. 28 is a schematic diagram of an optical tracking system accordingto a ninth embodiment of the present invention;

FIG. 29 is a schematic diagram of an optical tracking system accordingto a tenth embodiment of the present invention;

FIG. 30 is a schematic diagram of an optical tracking system accordingto an eleventh embodiment of the present invention;

FIG. 31 is a drawing showing a marker unit according to the eleventhembodiment of the present invention;

FIG. 32 is a flow chart explaining a process of calculating a directionof a target according to the eleventh embodiment of the presentinvention;

FIG. 33 is a flow chart explaining a spatial position and a direction ofa marker unit;

FIG. 34 is a flow chart explaining a direction of a marker unit;

FIG. 35 is a drawing explaining a process of calculating a direction ofa target using an optical tracking system of the eleventh embodiment;

FIG. 36 is a flow chart explaining a spatial position of a marker unit;and

FIGS. 37a-37d are drawings explaining a process of calculating a spatialposition of a marker unit.

MODE FOR INVENTION

The present invention is described more fully hereinafter with referenceto the accompanying drawings, in which example embodiments of thepresent invention are shown. The present invention may, however, beembodied in many different forms and should not be construed as limitedto the example embodiments set forth herein. Rather, these exampleembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the present invention tothose skilled in the art. In the drawings, the sizes and relative sizesof layers and regions may be exaggerated for clarity.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, and/or sectionsshould not be limited by these terms. These terms are only used todistinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component, orsection discussed below could be termed a second element, component, orsection without departing from the teachings of the present invention.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of thepresent invention. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Hereinafter, with reference to the drawings, preferred embodiments ofthe present invention will be described in detail.

An optical tracking system and method using the same according to anembodiment of the present invention attaches at least one marker on atarget such as a lesion or a surgical instrument, receives a parallellight emitted from the marker through the image forming unit and formsan enlarged image of a pattern portion on an image forming unit, andcalculates a spatial position and a direction of the target through aprocessor by using the enlarged image of the pattern portion. Thedetailed description is explained with reference to figures.

First Embodiment

FIG. 1 is a schematic diagram of a tracking system according to a firstembodiment of the present invention, and FIG. 2 is an example drawing ofa pattern portion of a marker unit.

Referring to FIGS. 1-2, a tracking system according to a firstembodiment of the present invention includes a marker unit 110, an imageforming unit 120, and a processor 130.

The marker unit 110 attached on a target and emits a parallel light toform an enlarged image of a pattern portion 111 which is included insidethe marker unit 110.

For example, the marker unit 110 may include a pattern portion 111, alight source 112, and a first lens portion 113.

The patter portion is formed by plurality of pattern portions 111 a in aregular shape with an interval. For example, the pattern portion 111 maybe formed to pass light except for an area in which pattern portions 111a are formed. Alternatively, the pattern portions 111 a may be formed topass light an area in which the pattern portions 111 a are formed.Alternatively, the pattern portion 111 may be formed to reflect lightemitted from the light source 112. Herein, the pattern portion 111 maybe arranged at a focal length of the first lens portion 113 which willbe described below.

The light source 112 irradiates light toward the pattern portion 111.For example, the light source 112 is arranged inside the marker unit 110to be positioned in a rear portion of the pattern portion 111. Asdescribed above, when the light source 112 is arranged in the rear ofthe pattern portion 111, the light emitted from the light source 112passes through the pattern portion 111 and is incident on the imageforming unit 120 described below. Alternatively, the light source 112may be arranged outside the marker unit 110. When the light source 112is arranged outside the marker unit 110, the light irradiated from thelight source 112 is reflected by the pattern portion 111 and is incidenton the image forming unit 120 described below. Herein the light source112 may be an LED (Light Emitting Diode).

The first lens portion 113 is arranged in front of the pattern portion111 to emit a parallel light toward the image forming unit 120 in whichthe light is irradiated from the light source 112 and has passed orreflected by the pattern portion 111. For example, the first lensportion 113 may be an objective lens to enlarge an image of the patternportion 111 and forming an enlarged image on the image forming unit 120.

The image forming unit 120 receives the parallel light of the patternportion 111 which is provided by the marker unit 110 and forms anenlarged image of the pattern portion 111. Herein, the image formingunit 120 may be a camera receiving the parallel light of the patternportion 111 which is provided by the marker unit 110 and forming theenlarged image of the pattern portion 111 on an image sensor 122.

The processor 130 is connected to the image forming unit 120, andcalculates a spatial position and a direction of the marker unit 120 byusing the enlarged image of the pattern portion 111 formed on the imageforming unit 120. Herein, the processor 130 may calculate a spatialposition of the marker unit 110 by using a position and a size change ofthe enlarged image of the pattern portion 111 formed on the imageforming unit 120. Also, the processor 130 may calculate a direction ofthe marker unit 110 by using a size change of the pattern portion 111 aand a position of the pattern portion for each area of the enlargedpattern portion 111.

Referring to FIGS. 1-7 d, a detailed process of calculating a spatialposition and a direction of a target using an optical tracking systemaccording to the first embodiment is explained below.

FIG. 3 is a flow chart explaining a method of tracking a target using anoptical tracking system according to a first embodiment, FIG. 4 is adrawing explaining a process of emitting light from a marker unit. FIG.5 is a drawing explaining a process of a parallel light being incidenton an image forming unit, FIG. 6 is a flow chart explaining a method ofcalculating a direction of a target using an optical tracking system ofthe first embodiment, FIGS. 7a-7d are drawings explaining a method ofcalculating a spatial position of a target using an optical trackingsystem according to a first embodiment, FIG. 8 is a flow chartexplaining a process of calculating of a spatial position and adirection of a marker unit, FIG. 9 is a flow chart explaining a processof calculating of a direction of a marker unit, and FIG. 10 is a flowchart explaining a process of calculating of a spatial position of amarker unit.

Referring to FIGS. 1-7 d, in order to track a target using an opticaltracking system according to the first embodiment of the presentinvention, first, a parallel light is emitted from the marker unit 120through the pattern portion 111 to form an enlarged image of the patternportion 111 (S110).

Explaining in detail the process of emitting a parallel light of apattern portion 111, first, a light is irradiated toward the patternportion 111 by operating a light source 112 such that a partial of thelight passes through or is reflected by the pattern portion 111. Thelight, which passes through or is reflected by the pattern portion 111,is emitted in a parallel light by passing a first lens portion 113formed by an objective lens as shown in FIG. 4.

The parallel light of the pattern portion 111, which has passed thefirst lens portion 113 emitted from a marker unit 110, is incident on animage forming unit to form an enlarged image of the pattern portion 111(S120).

Explaining in detail the process of forming the enlarged image of thepattern portion 111, the parallel light of the pattern portion, whichhas passed the first lens portion 113 and provided by the marker unit110, passes a lens portion 121 of the image forming unit 120 as shown inFIG. 5.

When the enlarged image of the pattern portion is formed on the imageforming unit 120, a spatial position and a direction of the marker unit110 are calculated through a processor 130 by using the enlarged imageof the pattern portion 111 (S130).

A detailed explanation of calculating the spatial position and thedirection of the marker unit 120 is explained with reference to FIG. 8.

FIG. 8 is a flow chart explaining a process of calculating of a spatialposition a direction of a marker unit.

Referring to FIG. 8, in order to calculate a spatial position and adirection of the marker unit 110, a direction of the marker unit 110 iscalculated by calculating a rotated angle of the marker unit 110 throughthe processor 130 by using the enlarged image of the pattern portion 111(S131).

When the rotated angle of the marker unit 110 is calculated, theprocessor calculates a spatial position of the marker unit 110 by usingthe rotated angle of the marker unit 110 and the enlarged image of thepattern portion 111 (S132).

Herein, a spatial position and a direction of the image forming unit 120is pre-stored in the processor 130.

A detailed explanation of calculating the direction of the marker unit120 is explained with reference to FIGS. 6 and 9.

FIG. 9 is a flow chart explaining a process of calculating of adirection of a marker unit.

Referring to FIG. 9, in order to calculate the direction of the markerunit 110, first, a position of the pattern portion 111 a and a sizechange of the pattern portion 111 a for each area of the enlarged imageof the pattern portion 111 formed on the image forming unit 120 aremeasured by the processor 130 (S1310).

When the position of the pattern portion 111 a and the size change ofthe pattern portion 111 a for each area are calculated, the direction ofthe marker unit 110 is calculated through the processor 130 bycalculating a rotated angle of the marker unit 110. The rotated angle ofthe marker unit is calculated by comparing a reference position of thepattern portion 111 a and a reference size change of the pattern portion111 a for each area of the enlarged pattern image of the patternportion, which are pre-stored in the processor 130, with the position ofthe pattern portion 111 a and the size change of the pattern portion 111a for each area of the enlarged image of the pattern portion 111 formedon the image forming unit 120 (S1311).

In other words, as shown in FIG. 6, the position and the size of thepattern portions 111 a of the enlarged image I₁ of the pattern portion111 formed on the image forming unit 120 are changed as the marker unit110 is rotated, and the processor 130 calculates the direction of themarker unit 110 by calculating the rotated angle of the marker unit 110by comparing the position and the size change of the pattern portion 111a for each area of the enlarged image I₁ of the pattern portion 111formed on the image forming unit 120 with the reference position of thepattern portion 111 a and reference size change of the pattern portion111 a for each area of the enlarged pattern image of the patternportion, which are pre-stored in the processor 130.

Next, a detailed explanation of calculating the spatial position of themarker unit 110 (S132) is explained with reference to FIGS. 7a-7d , and10.

FIG. 10 is a flow chart explaining a process of calculating a spatialposition of a marker unit.

Referring to FIG. 10, in order to calculate a spatial position of themarker unit 110, a position and a size of the enlarged image of thepattern portion 111 formed on the image forming unit 120 are measured bythe processor 130 (S1320).

After measuring the position and the size of the enlarged image of thepattern portion 111, a spatial position of the marker unit 110 portionis calculated by the processor 130 by comparing a reference position anda size of the image of the pattern portion 111 with the position and thesize of the enlarged image of the pattern (S1321).

FIG. 7a shows the reference position and the size of an image of thepattern portion 111 formed on the image forming unit 120 when the markeris positioned at a pre-stored position, which is stored in the processor130, and as shown in FIG. 7b , when a distance D2 between the markerunit 110 and the image forming unit 120 is shorter than a referencedistance D1, then, a size A2 of the enlarged image of the patternportion 111 formed on the image forming unit 120 is bigger than areference size A1 of the image of the pattern portion 111 which ispre-stored in the processor 130. Therefore, the spatial position of themarker unit 110 is calculated by comparing the reference size A1 of theimage of the pattern portion 111 with the size A2 of the enlarged imageof the pattern portion formed on the image forming unit 120.

Meanwhile, although it is not shown in the figure, when the distance D2between the marker unit 110 and the image forming unit 120 is longerthan the reference distance D1, then, the size A2 of the enlarged imageof the pattern portion 111 formed on the image forming unit 120 issmaller than the reference size A1 of the image of the pattern portion111 which is pre-stored in the processor 130.

And, when the marker unit is positioned below a reference position B1 asshown in FIG. 7b , the enlarged image of the pattern image of thepattern portion 111 is formed on the image forming unit 120 positioningabove a reference position C1 (Refer to FIG. 7a ) of the image of thepattern portion 111 which is pre-stored in the processor 130. Therefore,the spatial position of the marker unit 110 is calculated through theprocessor 130 by comparing the reference position C1 of the image of thepattern portion 111 with a position C2 of the enlarged image of thepattern portion 111 formed on the image forming unit 120.

Meanwhile, although it is not shown in the figure, when the marker unit110 is positioned at the reference position B1, the enlarged image ofthe pattern portion is formed on the image forming unit 120 positioningbelow the reference position C1 of the image of the pattern portion 111which is pre-stored in the processor 130.

And, when the distance D2 between the marker unit 110 and the imageforming unit 120 is different to the reference distance D1 and themarker unit 110 is not positioned at the reference position B1, thespatial position of the marker unit 110 is calculated by comparing theposition C2 and the size A2 of the enlarged image formed on the imageforming unit 120 with the reference position C1 and the reference sizeA1 of the image of the pattern portion 111 which is pre-stored in theprocessor 130.

Meanwhile, as shown in FIG. 7d , when the distance D2 between the markerunit 110 and the image forming unit 120 is identical to the referencedistance D1, the marker unit 110 is positioned at the reference positionB1 and the direction of the maker unit 110 is changed as θ, thecalculated size A2 and position C2 of the enlarged image of the patternportion 111 formed on the image forming unit 120 are identical to thereference position C1 and the reference size A1 of the image of thepattern portion 111 which is pre-stored in the processor 130. Therefore,the direction of the marker unit 111 is calculated by calculating therotated angle of the marker unit 111 by comparing the position for eachpattern portion 111 a and the size change of the pattern portion 111 aof the enlarged image I₁ of the pattern portion 111 with the referenceposition for each pattern portion 111 a and the reference size of thepattern portion 111 of the image I₂ of the pattern portion 111 which arepre-stored in the processor 130.

Second Embodiment

An optical tracking system according to an embodiment of the presentinvention is substantially the same as the optical tracking system ofthe first embodiment except for arranging two image forming units, adetailed explanation of other elements except for an arrangement of theimage forming unit is omitted.

FIG. 11 is a schematic diagram of a tracking system according to asecond embodiment of the present invention.

Referring to FIG. 11, an optical tracking system according to anembodiment of the present invention includes a maker unit 210, first andsecond image forming units 220 a and 220 b, and a processor 230.

The first and second image forming units 220 a and 220 b are arranged atan interval with the marker unit 210 as the center to receive a parallellight of the pattern portion 211 emitted from the marker unit 210 andform enlarged images of a pattern portion 211 which are different toeach other. Herein, it may be preferable to arrange the first and secondimage forming units 220 a and 220 b in a Y-axis as shown in FIG. 11.

The optical tracking system according to an embodiment of the presentinvention forms two enlarged images of the pattern portion 111 by thefirst and second image forming units 220 a and 220 b, calculates twospatial position coordinates of the marker unit 210 by the processor230, and therefore, calculates more precisely a spatial position and adirection of the marker unit 210 than the optical tracking system of thefirst embodiment.

A detailed explanation of calculating a spatial position and a directionof a marker unit using the optical tracking system according to anembodiment of the present invention is described in below with referenceto FIGS. 11 and 12.

FIG. 12 is a drawing explaining a process of calculating a spatialposition of a maker unit according to a second embodiment of the presentinvention.

As shown in FIG. 12, a coordinate of a first lens portion 213 of amarker unit 210 is defined as X, Y, and the coordinate of the first lensportion 213 may be represented as a Formula 1

X=f _(c) L/u ₁ +u ₂

Y=u ₁ L/u ₁ +u ₂  [Formula 1]

Herein, f_(c) is a coordinate of an X-axis of an enlarged patternportion 211 formed on a first and second image forming units 220 a and220 b, L is a coordinate of an Y-axis of a lens portion 221 b of thesecond image forming unit 220 b, u₁ is a coordinate of an Y-axis ofcentral coordinate of the enlarged pattern portion 211 formed on thefirst image forming unit 220 a, and u ₂ is a coordinate of an Y-axis ofcentral coordinate of the enlarged pattern portion 211 formed on thesecond image forming unit 220 a.

As shown in FIG. 12, when the first lens portion 213 of the marker unit210 is fixed and rotated as θ, real coordinates (X₁, Y₁) (X₂, Y₂) of thepattern portion 211 is represented as a Formula 2.

(X ₁ ,Y ₁)=(cos θf _(b)−sin θu ₁ ′+X,sin θf _(b)+cos θu ₁ ′+Y)

(X ₂ ,Y ₂)=(cos θf _(b)−sin θu ₂ ′+X,sin θf _(b)+cos θu ₂ ′+Y)  [Formula2]

Herein, the f_(b) is a focus length of the first lens portion 213 of themarker unit 210, and θ is rotated value of the marker unit 210.

And, a central coordinate of the enlarged pattern portion 211 formed onthe first image forming unit 220 a is defines as X₃, Y₃, and a centralcoordinate of the enlarged pattern portion 211 formed on the secondimage forming unit 220 b is defines as X₄, Y₄, as shown in FIG. 12, itis confirmed that a central coordinate of the enlarged pattern portion211 formed on the first image forming unit 220 a (X₃, Y₃), a centralcoordinate of the lens portion 221 a of the first image forming unit 220a (0,0), a central coordinate of the first lens 213 of the marker unit210 (X, Y), a real coordinate of the pattern portion 211 identified inthe first image forming unit 220 a (X₁, Y₁) are placed on Line1, and acentral coordinate of the enlarged pattern portion 211 formed on thesecond image forming unit 220 b (X₄, Y₄₎, a central coordinate of thelens portion 221 b of the second image forming unit 220 b (0,L), acentral coordinate of the first lens 213 of the marker unit 210 (X, Y),a real coordinate of the pattern portion 211 identified in the secondimage forming unit 220 a (X₂, Y₂) are placed on Line2. Herein, (X₃,Y₃)=(−f_(c)′, −u₁), (X₄, Y₄)=(−f_(c)′, L+u₂), and (X₁, Y₁) and (X₂, Y₂)may be represented as Formula 2.

As described above, each coordinate of Line1 and Line2 may berepresented using a Table 1.

TABLE 1 Coordinate Coordinate Real Coordinate of the lens of thecoordinate of the portion of enlarged of the pattern first lens theimage pattern portion (1) portion (2) forming unit (3) portion (4) Line1 X₁, Y₁ X, Y 0, 0 −f_(c)′, −u₁ Line 2 X₂, Y₂ X, Y 0, L −f_(c)′, L + u₂

Table 1 is an arranged table of coordinates which are placed on Line1and Line2, generating two equations using the three coordinates (1),(2), and (3), and the difference between the two equations may berepresented as Formula 3 with reference to the Table 1.

cos θX(u ₂ ′−u ₁′)+sin θY(u ₂ ′−u ₁′)L(cos θf _(b)−sin θu₂′)=0  [Formula 3]

Also, generating two equations using the three coordinates (1), (2), and(4) of the Line1 and Line2, and the difference between the two equationsmay be represented as Formula 4.

sin θY(u ₂ ′−U ₁′)+cos θf _(b)(u ₁ +u ₂)=sin θ(u ₁ ′u ₁ −u ₂ ′u ₂)+r ₁X(u ₂ ′−u ₁′)+cos θf _(c)(u ₂ ′−u ₁′)+L(cos θf _(b)−sin θu₂′)=0  [Formula 4]

Also, generating two equations using the three coordinates (1), (3), and(4) of the Line1 and Line2, and the difference between the two equationsmay be represented as Formulas 5 and 6.

u ₁ X+f _(c) Y+cos θ(u ₁ ′f _(c) −u ₁ f _(b))+sin θ(u ₁ ′u ₁ +f _(c) f_(b))=0  [Formula 5]

u ₂ +f _(C) Y+cos θ(u ₂ f _(b) +u ₂ ′+u ₂ ′f _(c))+sin θ(f _(b) f _(c)−u ₂ ′u ₂)−Lf _(c)=0  [Formula 6]

And tan θ is solved by substituting the Formula 3 to the Formula 4 anddividing into cos θ, and tan θ may be represented as Formula 7.

tan θ=sin θ/cos θ=[−f _(b)(u ₂ −u ₁)=f _(c)(u ₂ ′−u ₁′)]/u ₁ ′u ₁ −u ₂′u ₂  [Formula 7]

Meanwhile, the θ value is known in the Formulas 5 and 6, the onlyparameters X, Y may be calculated by solving simultaneous equationsconstituted by the Formulas 5 and 6, and the coordinate (X, Y) of thefirst lens portion 213 of the marker unit 210 may be represented asFormula 8.

X={[(u ₁ +u ₂)f _(b)−(u ₁ ′−u ₂′)f _(c)] cos θ−(u ₁ ′u ₁ −u ₂ ′u ₂)sinθ−Lf _(c)}/(u ₁ −u ₂)

Y={[(u ₁ ′u ₂ −u ₂ ′u ₁)f _(c)−2u ₁ u ₂ f _(b)] cos θ+[(u ₁ ′+u ₂′)u ₁ u₂−(u ₁ +u ₂)f _(b) f _(c)]sin θ+Lf _(c) u ₁)}/[(u ₁ −u ₂)f_(c)]  [Formula 8]

Third Embodiment

An optical tracking system according to an embodiment of the presentinvention is substantially the same as the optical tracking system ofthe first embodiment except for some elements, detailed explanations ofother elements except for a marker unit is omitted.

FIG. 13 is a schematic diagram of an optical tracking system accordingto a third embodiment of the present invention.

Referring to FIG. 13, an optical tracking system according to anembodiment of the present invention includes one marker unit 310, afirst image forming unit 320, and a processor 330.

The marker unit 310 may include a pattern portion 311, first and secondlight sources 312 a and 312 b, and first and second lens portions 313 aand 313 b.

The pattern portion 311 is formed by plurality of pattern portions (notshown) with an interval. Herein, two pattern portions 311 may be formedwhich are corresponding to the first and second lens portions 313 a and313 b as shown in FIG. 13, or, as well as one pattern portion 311 may beformed as shown FIG. 14, which will be described later.

The first and second light sources 312 a and 312 b are arranged on rearof the pattern portion 311 at an interval to irradiate lights toward thepattern portion 311.

The first and second lens portions 312 a and 312 b are formed in frontof the pattern portion 311 at an interval to release the lightsirradiated from the first and second light sources toward the patternportion 311 in parallel light form.

A process of calculating a direction of the marker unit 310 according toan embodiment of the present invention is omitted as it is the same asthe system of the first embodiment, and a process of calculating aspatial position of the marker unit 310 will be described with referenceto FIG. 14.

FIG. 14 is a drawing explaining a process of calculating a spatialposition of a marker unit according to the third embodiment of thepresent invention.

As shown in FIG. 14, a coordinate of an image formed on the imageforming unit 320 is defined as u₁,u₂, a real coordinate (X₁, Y₁) of thepattern portion 311, which passes a central coordinate (X, Y) of thefirst lens portion 313 a of the marker unit 310 and meets the patternportion 311, may be represented as a Formula 9.

(X ₁ ,Y ₁)=(cos θf _(b)−sin θu ₁ ′+X,sin θf _(b)+cos θu ₁ ′+Y)  [Formula9]

Also, a real coordinate (X₂, Y₂) of the pattern portion 311, whichpasses a central coordinate (−sin θ1+X, cos θ1+Y) of the second lensportion 313 b and meets the pattern portion 311, may be represented asFormula 10.

(X ₂ ,Y ₂)=(cos θf _(b)−sin θ(1+u ₂′)+X,sin θf _(b)+cos θ(1+u₂′)+Y)  [Formula 10]

Meanwhile, each of coordinate of Line1 and Line2 may be representedusing a Table 2 in the same manner as the second embodiment.

TABLE 2 Coordinate Real Coordinates of Coordinate of the of thecoordinate the first and lens portion of enlarged of the pattern secondlens the image pattern portion (1) portions(2) forming unit (3) portion(4) Line 1 X₁, Y₁ X, Y 0, 0 −f_(c)′, −u1 Line 2 X₂, Y₂ −sinθ₁ + X, 0, 0−f_(c)′, L + u2 cos θ₁ + Y

Table 2 is an arranged table of coordinates placed on Line1 and Line2,generating two equations using the three coordinates (2), (3) withreference to the Table 2, and (4), X, Y may be represented as Formula11.

X=[(cos θf _(c)+sin θu ₂)/(u ₂ −u ₁)]1,Y=[(cos θf _(c)+sin θu ₂)/(u ₂ −u₁)](1u ₁ /f _(c))  [Formula 11]

Also, generating two equations using the three coordinates (1), (2), and(3) of the Line1 and Line2, and the difference between the two equationsmay be represented as Formula 12.

cos θX(u ₂ ′−u ₁′)+sin θY(u ₂ ′−u ₁′)−1f=0  [Formula 12]

Also, generating two equations using the three coordinates (1), (2), and(4) of the Line 1 and Line2, and the difference between the twoequations may be represented as Formula 13.

cos θ[f _(c)(u ₂ ′−u ₁′)−f _(b)(u ₂ −u ₁)]+sin θ[u ₂ u ₂ ′−u ₁ u ₁′]+cosθX(u ₂ ′−u ₁′)+sin θY(u ₂ ′−u ₁′)−1f=0  [Formula 13]

Also, generating two equations using the three coordinates (1), (3), and(4) of the Line1 and Line2, and the two equations may be represented asFormulas 14 and 15.

u ₁ X−f _(c) Y+cos θ(u ₁ f _(b) −u ₁ ′f _(c))−sin θ(f _(b) f _(c) +u ₁ u₁′)=0  [Formula 14]

u ₂ X−f _(c) Y+cos θ(u ₂ f _(b) −u ₂ ′f+1f _(c))−sin θ(u ₂ u ₂′+1u ₂ +f_(b))=0  [Formula 15]

Meanwhile, substituting the Formula 12 to the Formula 13 and dividinginto cos θ, and tan θ may be represented as Formula 16.

tan θ=sin θ/cos θ=[f _(c)(u ₂ ′−u ₁′)−f _(b)(u ₂ −u ₁)]/(u ₂ u ₂ ′−u ₁ u₁′)  [Formula 16]

And, the θ value is known in the Formulas 14 and 15, the only parameterX, Y may be calculated by solving simultaneous equation constituted bythe Formulas 14 and 15, and the coordinate (X, Y) of the first lensportion 313 a of the marker unit 210 may be represented as Formula 17.

X={cos θ[f _(c)(u ₂ ′−u ₁′)−f _(b)(u ₂ −u ₁)−1f _(c)]+sin θ(u ₂ u ₂ ′−u₁ u ₁ ′+f _(b) f _(c)+1u ₂ +f _(b))}/(u ₂ −u ₁)

Y={cos θf _(c)(u ₂ u ₁ ′−u ₁ u ₂′+1)+sin θ[u ₁ u ₂(u ₁ ′−u ₂′−1)+u ₁ f_(b) +u ₂ f _(b) f _(c)]}/[(u ₁ −u ₂)f _(c)]  [Formula 17]

Also, coordinate (−sin θ₁+X, cos θ1+Y) of the second lens portion 313 bis also calculated since the coordinate of the first lens portion 313 ais calculated.

Fourth Embodiment

An optical tracking system according to the present invention issubstantially the same as the optical tracking system of the firstembodiment except for arranging two maker units, detailed explanationsof other elements except for an arrangement of an image forming unit anda marker unit is omitted.

FIG. 15 is a schematic diagram of an optical tracking system accordingto a fourth embodiment of the present invention.

Referring to FIG. 15, an optical tracking system according to anembodiment of the present invention includes first and second markerunits 410 a and 410 b, first and second image forming units 420 a and420 b, and a processor 430.

The first and second marker units 410 a and 410 b are attached on atarget at an interval, and a spatial position and a direction betweenthe first and second marker units are pre-stored in the processor 430.

The first and second image forming units 420 a and 420 b receiveparallel lights of a pattern portions 4111 a and 411 b which are emittedfrom each of the first and second marker units 410 a and 410 b to forman enlarged image. In other words, the first image forming unit 420 aforms an enlarged image by receiving the parallel light of the patternportion 411 a which is emitted from the first marker unit 420 a, and thesecond image forming unit 420 b forms an enlarged image by receiving theparallel light of the pattern portion 411 b which is emitted from thesecond marker unit 420 b.

The processor 430 is connected to the first and second image formingunits 420 a and 420 b, and calculates a spatial position and a directionof the first and second marker units 410 a and 410 b by using theenlarged images of the pattern portion 411 a and 411 b formed on thefirst and second image forming units 420 a and 420 b.

FIG. 16 is a drawing explaining a process of calculating a spatialposition of a marker unit according to the fourth embodiment of thepresent invention.

As shown in FIG. 16, an optical tracking system according to anembodiment of the present invention calculates through a processor 430 avector from a center of a lens portion 421 a of a first image formingunit 420 a to a center of a first lens portion 413 a of a first markerunit 410 a, a vector from a center of a lens portion 421 b of a secondimage forming unit 420 b to a center of a second lens portion 413 b of asecond marker unit 410 b, and a spatial position and a direction of thefirst and second marker units 410 a and 410 b by calculating anintersection point between two straight line equations of l_(l) andl_(r), in which the two straight line equations l_(l) and l_(r) aregenerated from the two vectors.

Fifth Embodiment

FIG. 17 is a schematic diagram of an optical tracking system accordingto a fifth embodiment of the present invention.

Referring to FIGS. 17 and 18, an optical tracking system according to anembodiment of the present invention includes at least one light source540, at least one marker unit 510, at least one image forming unit 520,and a processor 530.

The at least one light source is arranged to irradiated a light towardthe marker unit 410. For example, the light source 540 may be an LED(Light Emitting Diode). Herein, it may be preferable to arrange the atleast one light source 540 outside the marker unit 510.

The at least one marker unit 510 reflects the light emitted from thelight source 540 in a parallel light.

The marker unit 510 may include a ball lens 513 in which a patternportion 511 is formed on a surface of the ball lens 513. Herein, thepattern portion 511 may be entirely formed on the surface of the balllens 513. Alternatively, the pattern portion 511 may be partially formedon the surface of the ball lens 513.

The ball lens 513 reflects the light irradiated from the light source540 toward the image forming unit 520 to form an enlarged image of thepattern portion 511 on the image forming unit 520.

The at least one image forming unit 520 receives the parallel lightprovided by the marker unit 510 and forms an enlarged image of thepattern portion 511.

For example, the image forming unit 520 may be a camera which receivesthe parallel light provided by the marker unit 510 through a lensportion 521 and forms an image of the pattern portion 511 on a sensorportion 522 which is enlarged by the parallel light.

The processor 530 calculates a spatial position of the marker unit 510by comparing the enlarged image of the pattern portion 511 formed on theimage forming unit 520 with a reference image of the pattern portion 511stored in the processor 530.

In more detail, the processor 530 calculates a spatial position of themarker unit 510 by comparing a position and a size of an enlarged imageof the pattern portion 511 formed on the image forming unit 520 with apre stored position and size of reference image of the pattern, adirection of the marker unit 510 by comparing a position and a size ofthe pattern portion 511 for each area of the enlarged image of thepattern portion 511 with a pre-stored position of reference patternportion and a size of the reference pattern portion for each area, and aspatial position and a direction of a target by using the spatialposition and the direction of the marker unit 510.

A process of calculating a spatial position and a direction of a targetby using the fifth embodiment is explained with reference to FIGS. 17 to24.

FIG. 19 is a flow chart explaining a method of tracking a target usingan optical tracking system according to the fifth embodiment.

Referring to FIGS. 17-19, in order to track a target using an opticaltracking system according to the fifth embodiment, first, a light isirradiated toward a marker unit 510, in other word, towards a ball lenson which a pattern portion 51 is formed, by operating a light source 540(S210).

Then, the light irradiated toward the marker unit 510 is reflected bythe pattern portion 511, which is formed on a surface of the ball lens513, in a parallel light (S220).

The parallel light reflected by the ball lens 513 is incident on animage forming unit 520 to form an enlarged image of the pattern portion511 (S230).

Explaining the step of forming an enlarged image of the pattern portion511 (S230) in more detail, the parallel light of the pattern portion 511reflected by the ball lens 513 passes a lens portion 512 of the imageforming unit 520, and an enlarged pattern portion 511 is formed on asensor portion 522 by the parallel light which have passed the lensportion 521 of the image forming unit 520.

When the enlarged image of the pattern portion 511 is formed on theimage forming unit 520 as described above, then, a spatial position anda direction of the marker unit 510 is calculated by using the enlargedimage of the pattern portion 511 (S240).

A detailed process of calculating a spatial position and a direction ofthe marker unit 510 is explained below with reference to FIG. 20.

FIG. 20 is a flow chart explaining a process of calculating a spatialposition and a direction of a marker unit.

Referring to FIG. 20, in order to calculate a spatial position and adirection of a marker unit, a direction of the marker unit 510 iscalculated through the processor 530 by calculating a rotated angle ofthe marker unit 510 by using the enlarged image of the pattern portion511 formed on the image forming unit 520 (S241).

When a rotated angle of the marker unit 510 is calculated by theprocessor 530, a spatial position of the marker unit 510 is calculatedthrough the processor 530 by using the enlarged image of the patternportion 511 formed on the image forming unit 520 and the rotated angleof the marker unit 510 (S242).

Herein, a spatial position and a direction of the image forming unit 520is pre-stored in the processor 530.

A detailed process of calculating a direction of the marker unit 510(S241) is explained below with reference to FIGS. 21 and 22.

FIG. 21 is a flow chart explaining a process of calculating a directionof a marker unit, and FIG. 22 is a drawing explaining a process ofcalculating a direction of a target using an optical tracking system ofthe first embodiment.

Referring to FIG. 21, in order to calculate a direction of the markerunit 510, first, a position for each area of the enlarged image of thepattern portion 511 formed on the image forming unit 520 and a sizechange of the pattern portion 511 is measured (S1410).

After measuring the position and the size change of the pattern portion511 for each area of the enlarged image of the pattern portion 511,then, the a direction of the marker unit 510 is calculated bycalculating a rotated angle of the marker unit 510 by comparing areference position of the pattern portion and a reference size of thepattern portion for each area which are pre-stored in the processor 530with the position and the size change of the pattern portion 511 foreach area of the enlarged image of the pattern portion 511 formed on theimage forming unit 520 (S2411).

In other words, as shown in FIG. 22, the position and the size of theenlarged image of the pattern portion 511 formed on the image I₁ formingunit 520 is changed when the marker unit 510 is rotated, and therefore,a direction of the marker unit 510 is calculated by calculating therotated angle θ of the marker unit 510 by comparing a position and asize change of the pattern portion 511 for each area of the enlargedimage I₁ with the reference position of the pattern portion 511 and areference size of pattern portion for each area of the image I₂ of thepattern portion 511 which are pre-stored in the processor 530. Next, adetailed process of calculating a spatial position of the marker unit510 (S242) is explained below with reference to FIGS. 23 to 24 d.

FIG. 23 is a flowchart explaining a process of calculating a spatialposition of a marker unit, and FIGS. 24a-24d are drawings explaining aprocess of calculating a spatial position of a marker unit.

Referring to FIGS. 23 to 24 d, in order to calculate a spatial positionof a marker unit 510, first, a position and a size of the enlarged imageof the pattern portion 511 formed on the image forming unit 520 iscalculated by the processor 530 (S2420).

After calculating the position and the size of the image of the patternportion 511, a spatial position of the marker unit 510 is calculated bycomparing the position and the size of the enlarged image of the patternportion 511 formed on the image forming unit 520 with the referenceposition and size of the image of the pattern portion 511 which arepre-stored in the processor 530 (S2421).

FIG. 24a shows a reference position and a size of an image of thepattern portion 511 formed on the image forming unit 520 when the markerunit 510 is at a position which is pre-stored in the processor 530, whena distance D2 between the marker unit 510 and the image forming unit 520is shorter than a reference distance D1 as shown in FIG. 24b , a size A2of the enlarged image of the pattern portion 511 formed on the imageforming unit 520 is bigger than a reference size A1 of the image of thepattern portion 511 which is pre-stored in the processor 530. Therefore,a spatial position of the marker unit 510 is calculated through theprocessor 530 by comparing the enlarged image size A2 of the patternportion 511 formed on the image forming unit 520 with the referenceimage size A1 of the pattern portion 511.

Meanwhile, although it is not shown in the figure, when the distance D2between the marker unit 110 and the image forming unit 120 is longerthan the reference distance D1, then, the size A2 of the enlarged imageof the pattern portion 511 formed on the image forming unit 520 issmaller than the reference size A1 of the image of the pattern portion511 which is pre-stored in the processor 530.

And, when the marker unit 510 is positioned below a reference positionB1 as shown in FIG. 24c , the enlarged image of the pattern portion 511is formed on the image forming unit 520 above a reference position C1(Refer to FIG. 24a ) which is pre-stored in the processor 530.Therefore, a spatial position of the marker unit 510 is calculatedthrough the processor 530 by comparing the reference position C1 of theimage of the pattern portion with the position C2 of the enlarged imageof the pattern portion 511 formed on the image forming unit 520.

Meanwhile, although it is not shown in the figure, when the marker unit510 is positioned above the reference position B1, then, the enlargedimage of the pattern portion 511 is formed on the image forming unit 520below the reference position C1 (Refer to FIG. 24a ) which is pre-storedin the processor 530.

And, when the distance D2 between the marker unit 510 and the imageforming unit 520 is different to the reference distance D1 and themarker unit 510 is not positioned at the reference position B1, aspatial position of the marker unit 510 is calculated by comparing theposition C2 and the size A2 of the enlarged image formed on the imageforming unit 520 with the reference position C1 and the reference sizeA1 of the image of the pattern portion 511 which is pre-stored in theprocessor 530.

Meanwhile, as shown in FIG. 24d , when the distance D2 between themarker unit 510 and the image forming unit 520 is identical to thereference distance D1, the marker unit 510 is positioned at thereference position B1 and the direction of the maker unit 510 is changedas θ, the calculated size A2 and position C2 of the enlarged image ofthe pattern portion 511 formed on the image forming unit 520 areidentical to the reference position C1 and the reference size A1 of theimage of the pattern portion 111 which is pre-stored in the processor530. Therefore, a direction of the marker unit 511 is calculated bycalculating the rotated angle of the marker unit 511 by comparing theposition for each pattern portion 511 a and the size change of thepattern portion 511 a of the enlarged image I₁ of the pattern portion511 with the reference position for each pattern portion 511 a and thereference size of the pattern portion 511 of the image I₂ of the patternportion 511 which are pre-stored in the processor 530.

As described above, an optical tracking system according to anembodiment of the present invention emits a parallel light of a patternportion 511 from a marker unit 510, forms an enlarged image of thepattern portion 511 on an image forming unit 520, and calculates aspatial position of the marker unit 510 using the enlarged image of thepattern portion 511. In other words, the spatial position and thedirection of a target to be calculated are calculated without areduction of accuracy by enlarging an image of the pattern portion 511and forming the image on the image forming unit 520, and therefore, anaccuracy of the position of the marker unit is not dependent to aresolving power.

Therefore, an optical tracking system and a method using the sameaccording to an embodiment of the present invention has an effect ofexpanding an available area by detecting an exact spatial position and adirection of a target regardless of a distance from the target to becalculated, as well as, a system downsizing is also achieved comparedwith conventional system by reducing size of a marker unit 510.

Sixth Embodiment

An optical tracking system according to a sixth embodiment of thepresent invention is described below with reference to FIG. 25.

FIG. 25 is a schematic diagram of an optical tracking system accordingto a sixth embodiment of the present invention.

Referring to FIG. 25, an optical tracking system according to anembodiment of the present invention may include at least one lightsource (not shown), a maker unit 610, first and second image formingunits 620A and 620B, and a processor 630.

As shown in FIG. 25, an optical tracking system according to anembodiment may be formed by a maker unit 610 in which a pattern portion611 is formed on a surface of the marker unit 610, first and secondimage forming units 620 a and 620 b arranged with the marker unit 610 asthe center, and the processor connected to the first and second imageforming units 620 a and 620 b.

Therefore, each of the first and second image forming units 620 a and620 b receives a parallel light provided by the marker unit 610 andforms an enlarged image of the pattern portion 611, for example, theimage forming units 620 a and 620 b may be a camera which receives theparallel light provided by the marker unit 610 through each of lensportions 621 a and 621 b and forms images of the pattern portion 611which are enlarged by the parallel light on each sensor portions 622 aand 622 b.

The processor 630 calculates a spatial position and a direction of themarker unit 610 by comparing the enlarged image of the pattern portion611 formed on each of the first and second image forming units 620 a and620 b with a reference image of the pattern portion which is pre-storedin the processor 630. Herein, a spatial position and a direction of thefirst and second image forming units 620 a and 620 b and the at leastone light source are pre-stored in the processor 630.

Seventh Embodiment

An optical tracking system according to a seventh embodiment of thepresent invention is described below with reference to FIG. 26.

FIG. 26 is a schematic diagram of an optical tracking system accordingto a seventh embodiment of the present invention.

Referring to FIG. 26, an optical tracking system according to anembodiment of the present invention may include at least one lightsource (not shown), first to third marker units 710 a 710 b and 710 c,an image forming unit 720, and a processor 730.

As shown in FIG. 26, in an optical tracking system according to anembodiment, first to third maker units 711 a 710 b and 710 c, in whichball lenses 713 a 713 b and 713 c are formed with pattern portions 711 a711 b 711 c on their surfaces in the first to third maker units 711 a710 b and 710 c, are arranged on a target at an interval, the first tothird marker units 710 a 710 b and 710 c reflect a light emitted fromthe light source in a parallel light, and the image forming unit 720receives the parallel light emitted from the first to third marker units710 a 710 b and 710 c and forms an enlarged image of pattern portions711 a 711 b and 711 c.

Meanwhile, the processor 730 calculates a spatial position and adirection of the marker unit 710 by comparing the enlarged image of thepattern portion 711 a 711 b and 711 c of the first to third marker units710 a 710 b and 710 c formed on the image forming unit 720 with areference image of the pattern portion which is pre-stored in theprocessor 730. Herein, a spatial position and a direction of the imageforming unit 720 and the at least one light source are pre-stored in theprocessor 730.

Also, geometric information of the first to third marker units 710 a 710b and 710 c attached on the target are pre-stored in the processor 730.

Herein, the geometric information of the first to third marker units 710a 710 b and 710 c may be length information of straight lines L1 L2 andL3 which virtually connect the adjacent marker units 710 a 710 b and 710c and angle information θ1 θ2 and θ3 formed by the pair of straightlines L1 L2 L3 which virtually connect the adjacent marker units 710 a710 b and 710 c.

Eighth Embodiment

An optical tracking system according to an eighth embodiment of thepresent invention is described below with reference to FIG. 27.

FIG. 27 is a schematic diagram of an optical tracking system accordingto an eighth embodiment of the present invention.

Referring to FIG. 27, an optical tracking system according to anembodiment is substantially the same as the seventh embodiment exceptfor an addition of a second image forming unit 820 b.

In other words, as shown in FIG. 27, in an optical tracking systemaccording to an embodiment, the first to third marker units 810 a 810 band 810 c, in which pattern portions 811 a 811 b and 811 c are formed onsurfaces of ball lenses 813 a 83 b and 813 c included in the first tothird marker units 810 a 810 b and 810 c, are attached on a target at aninterval, and first and second image forming units 820 a and 820 b arearranged with the first to third marker units 810 a 810 b and 810 c asthe center, and a processor 830 is connected to the first and secondimage forming units 820 a and 820 b.

And, the image forming units 820 a and 820 b receive a light emittedfrom the light source which is reflected by the first to third markerunits 810 a 810 b in a parallel light and form enlarged images of thepattern portions 811 a 811 b and 811 c.

The image forming units 820 a and 820 b receive the parallel lightemitted from the first to third marker units 810 a 80 b and 810 cthrough a lens portions 821 a and 821 b and form enlarged images of thepattern portions 811 a 811 b and 811 c on a sensor portions 822 a and822 b.

Ninth Embodiment

An optical tracking system according to an embodiment is substantiallythe same as the fifth embodiment except for some details of a markerunit, detailed explanations of other elements except for some contentassociated with a marker unit are omitted.

FIG. 28 is a schematic diagram of an optical tracking system accordingto a ninth embodiment of the present invention.

Referring to FIG. 28, a marker unit 910 of an optical tracking systemaccording to an embodiment of the present invention may include apattern portion 911 and a fisheye lens 913.

The pattern portion 911 may reflect or pass a light emitted from atleast one light source (not shown). In other words, it may be preferableto make the pattern portion 91 to reflect the light emitted from thelight source when the light source is arranged outside the marker unit910, or to pass the light emitted from the light source when the lightsource is arranged inside the marker unit 910.

The fisheye lens 913 is arranged in front of the pattern portion 911 topass and release the light, which is emitted from the light source andreflected by or having passed the pattern portion 911, toward an imageforming unit (not shown) in parallel light shape.

Herein, it may be preferable to arrange the pattern portion 911 at afocal length of the fisheye lens 913.

Tenth Embodiment

An optical tracking system according to an embodiment is substantiallythe same as the first embodiment except for some details of a makerunit, detailed explanations of other elements except for some contentassociated with a marker unit are omitted.

FIG. 29 is a schematic diagram of an optical tracking system accordingto a tenth embodiment of the present invention.

Referring to FIG. 29, a marker unit 1010 of an optical trackingaccording to an embodiment of the present invention may include apattern portion 1011, an objective lens 1013, and a prism 1014.

The pattern portion 1011 may reflect or pass a light emitted from atleast one light source (not shown). In other words, it may be preferableto make the pattern portion 1011 to reflect the light emitted from thelight source when the light source is arranged outside the marker unit1010, or to pass the light emitted from the light source when the lightsource is arranged inside the marker unit 1010.

The objective lens 1013 is arranged in front of the pattern portion 1011to pass and release the light, which is emitted from the light sourceand reflected by or having passed the pattern portion 1011, toward animage forming unit (not shown) in parallel light form.

Herein, it may be preferable to arrange the pattern portion 1011 at afocal length of the objective lens 1013.

The prism 1014 passes the light having passed the objective lens 1013and makes the light to be incident on an image forming unit afterextending an angle of view of the parallel light. Herein, it may bepreferable to form the prism 1014 in a pyramid shape.

Eleventh Embodiment

FIG. 30 is a schematic diagram of an optical tracking system accordingto an eleventh embodiment of the present invention, and FIG. 31 is adrawing showing a marker unit according to the eleventh embodiment ofthe present invention.

Referring to FIGS. 31 and 32, an optical tracking system according to anembodiment of the present invention includes at least one light source1140, at least one marker unit 1110, at least one image forming unit1120, and a processor 1130.

The at least one light source 140 is arranged to emit a light toward themarker unit 1110. For example, the light source may be an LED (LightEmitting Diode). Herein, it may be preferable to arrange the at leastone light source 1140 outside the marker unit 1110.

The at least one marker unit 1110 reflects the light emitted from thelight source 1140 in a parallel light, and an enlarged image of thepattern portion 1111 is formed on the image forming unit 1120 by theparallel light.

The marker unit 1110 may include a mirror portion 1113 and a patternportion 1111.

The mirror portion 1113 reflects the light, which is emitted from the atleast one light source 1140 toward the marker unit 1110, toward thepattern portion 1111, re-reflects the light reflected by the patternportion 1111, and provides the light toward the image forming unit in aparallel light form. Herein, the mirror portion 1113 is a mirror with aspherical or non-spherical shape. For example, a concave mirror may beused as the mirror portion 1113 to gather and reflect the light in onepoint.

The pattern portion 1111 is arranged at a focal distance of the mirrorportion 1113 to re-reflect the incident light which is reflected by themirror portion 1113.

Meanwhile, the marker unit 1110 may further include a first lens 1112.

The first lens 1112 may be arranged at a focal length of the mirrorportion 1113. In other words, the first lens 1112 is arranged at alocation apart from the mirror portion 1113 by a focal distance of themirror portion 1113 such that the parallel light reflected by the mirrorportion 1113 is provided once more in parallel light form toward the atleast one image forming unit 1120.

Meanwhile, the marker unit 1110 may further include an apertureinstalled on the mirror portion 1113. The aperture 1114 adjusts a lightquantity of the light, which is emitted from the light source 1140 andincident on the mirror portion 1113, to adjust an angle of view and aresolution of an enlarged image of the pattern portion 1111.

The at least one image forming unit 1120 forms an enlarged image of thepattern portion 1111 by receiving the parallel light which is providedfrom the marker unit 1110.

For example, the image forming unit 1120 may be a camera which receivesthe parallel light provided by the marker unit 1110 through the patternportion 1111 and forms an enlarged image of the pattern portion 1111 onan image sensor portion 1122.

The processor 1130 calculates a spatial position and a direction of themarker unit 1110 by comparing the enlarged image of the pattern portion1111 with a reference image of the pattern portion pre-stored in theprocessor 1130.

In more detail, the processor 1130 calculates a spatial position and adirection of the marker unit 1110 by comparing a position and a size ofthe enlarged image of the pattern portion 1111 formed on the imageforming unit 1120 with a pre-stored reference position and size of areference image of the pattern portion 1111, a direction of the markerunit 1110 by comparing a position and a size of the pattern portion 1111for each area of the enlarged image of the pattern portion 1111 with apre-stored reference position and reference size of the image of thepattern portion 1111 for each area, and therefore, calculates a spatialposition and a direction of a target by using the spatial position anddirection of the marker unit 1110.

A process of calculating a spatial position and a direction of a targetaccording to the eleventh embodiment is described below with referenceto FIGS. 30-37.

FIG. 32 is a flow chart explaining a process of calculating a directionof a target according to the eleventh embodiment of the presentinvention.

Referring to FIGS. 32-32, in order to track a target using an opticaltracking system according to the eleventh embodiment, first, a light isirradiated toward a maker unit 1110 by operating a light source 1140, inother words, the light is irradiated toward a mirror portion 1113 onwhich a pattern portion is formed on (S310).

The light irradiated toward the marker unit 1110 is reflected by markerunit 1110, in which the pattern portion 1111 is formed at a focal lengthof the mirror portion 1113, in a parallel light to form an enlargedimage of the pattern portion 1111 (S320).

In more detail, the light irradiated toward the marker unit 1110 isreflected by the mirror portion and gathered in one point of the patternportion 1111, re-reflected by the pattern portion 1111 and the mirrorportion 1113 in a parallel light, and the parallel light is emitted oncemore in a parallel light through a first lens 1112.

The parallel light reflected by the marker unit 1110 is incident on animage forming unit and forms an enlarged image of the pattern portion1111 (S330).

Explaining in detail the process of forming the enlarged image of thepattern portion 1111, the parallel light of the pattern portion 1111which is reflected by the marker unit 1110 passes a lens portion 1121 ofthe image forming unit 1120, the parallel light, which have passed thelens portion 1121 of the image forming unit 1120, forms the enlargedimage of the pattern portion 1111 on a sensor part 1122.

When the enlarged image of the pattern portion 1111 is formed on theimage forming unit 1120, an angle of view and a resolution of theenlarged image of the pattern portion 1111 are adjusted by adjusting alight quantity of the light which is incident on the mirror portion 1113by operating an aperture 1114 after verifying an image formation (S340).

After adjusting the view of angle and the resolution of the enlargedimage of the pattern portion 1111 by adjusting the light quantity of thelight which is incident on the mirror portion by the aperture 1114, aspatial position and a direction of the marker unit 1110 are calculatedthrough the processor 1130 by using the enlarged image of the patternportion 1111 in which the view of angle and the resolution are adjusted(S350).

The process of calculating the spatial position and the direction of themarker unit 1110 (S150) is described below with reference to FIG. 33.

FIG. 33 is a flow chart explaining a spatial position and a direction ofa marker unit.

Referring to FIG. 33, in order to calculate a spatial position and adirection of the marker unit 1110 through the processor 1130, thedirection of the marker unit 1110 is calculated by calculating a rotatedangle of the marker unit 1110 by using the enlarged image of the patternportion 1111 formed on the image forming unit 1120 (S351).

After calculating the rotated angle of the marker unit 1110 through theprocessor 1130, the spatial position of the marker unit 1110 iscalculated through the processor 1130 by using the enlarged image of thepattern portion 1111 formed on the image forming unit 1120 and therotated angle of the marker unit 1110 (S352).

Herein, a spatial position and a direction of the image forming unit1120 are pre-stored in the processor 1130.

A detailed process of calculating the direction of the marker unit 1110(S351) is described below with reference to FIGS. 34 and 35.

FIG. 34 is a flow chart explaining a direction of a marker unit, andFIG. 35 is a drawing explaining a process of calculating a direction ofa target using an optical tracking system of the eleventh embodiment.

Referring to FIG. 34, in order to calculated the direction of the markerunit 1110, first, positions for each area of pattern portion 1111 and asize change of the pattern portion 1111 of the enlarged image of thepattern portion 1111 are measured (S3510).

After measuring the positions for each area of pattern portion 1111 andthe size change of the pattern portion 1111, the direction of the markerunit 1110 is calculated by calculating the rotated angle of the markerunit 1110 by comparing the position and the size change of the patternportion 1111 for each area of the enlarged image of the pattern portion1111 formed on the image forming unit 1120 with a reference position ofand a reference size of the pattern portion for each area of an image ofthe pattern portion 1111 which are pre-stored in the processor 1130(S3511).

In other words, as shown in FIG. 35, a position and a size of thepattern portion 1111 of the enlarged image I₁ of the pattern portion1111 formed on the image forming unit 1120 are changed as the markerunit 1110 is rotated, and the processor 1130 calculates the direction ofthe marker unit 1110 by calculating the rotated angle of the marker unit1110 by comparing the position and the size change of the patternportion 1111 for each area of the enlarged image I₁ of the patternportion 1111 formed on the image forming unit 1120 with the referenceposition and the reference size change for each area of the patternportion 1111 of the enlarged pattern image of the pattern portion, whichare pre-stored in the processor 1130.

Next, a detailed process of calculating the spatial position of themarker unit 1110 (S352) is described below with reference to FIGS. 36and 37.

FIG. 36 is a flow chart explaining a spatial position of a marker unit,and FIGS. 37a-37d are drawings explaining a process of calculating aspatial position of a marker unit.

Referring to FIGS. 36-37 d, in order to calculated the spatial positionof the marker unit 1110, first, a position and a size change of theenlarged image of the pattern portion 1111 are measured (S3520).

After measuring the position and the size change of the enlarged imageof the pattern portion 1111, the spatial position of the marker unit1110 is calculated through the processor 1130 by comparing the positionand the size change of the enlarged image of the pattern portion 1111formed on the image forming unit 1120 with a reference position and areference size of the image of the pattern portion 1111 which arepre-stored in the processor 1130 (S3521).

FIG. 37a shows the reference position and the size of the image of thepattern portion 1111 formed on the image forming unit 1120 when themarker unit 1110 is positioned on the pre-stored position, and as shownin FIG. 317b , when a distance D2 between the marker unit 110 and theimage forming unit 1120 is shorter than a reference distance D1, then, asize A2 of the enlarged image of the pattern portion 1111 formed on theimage forming unit 1120 is bigger than a reference size A1 of the imageof the pattern portion 1111 which is pre-stored in the processor 1130.Therefore, the spatial position of the marker unit 1110 is calculated bycomparing the reference size A1 of the image of the pattern portion 1111with the size A2 of the enlarged image of the pattern portion formed onthe image forming unit 1120.

Meanwhile, although it is not shown in the figure, when the distance D2between the marker unit 1110 and the image forming unit 1120 is longerthan the reference distance D1, then, the size A2 of the enlarged imageof the pattern portion 1111 formed on the image forming unit 1120 issmaller than the reference size A1 of the image of the pattern portion1111 which is pre-stored in the processor 1130.

And, when the marker unit 1110 is positioned below a reference positionB1 as shown in FIG. 37c , the enlarged image of the pattern image of thepattern portion 1111 is formed on the image forming unit 1120positioning above of a reference position C1 (Refer to FIG. 37a ) of theimage of the pattern portion 1111 which is pre-stored in the processor1130. Therefore, the spatial position of the marker unit 1110 iscalculated through the processor 1130 by comparing the referenceposition C1 of the image of the pattern portion 1111 with a position C2of the enlarged image of the pattern portion 1111 formed on the imageforming unit 1120.

Meanwhile, although it is not shown in the figure, when the marker unit1110 is positioned at the reference position B1, the enlarged image ofthe pattern portion 1111 is formed on the image forming unit 120positioning below of the reference position C1 of the image of thepattern portion 1111 which is pre-stored in the processor 1130.

And, when the distance D2 between the marker unit 1110 and the imageforming unit 1120 is different to the reference distance D1 and themarker unit 110 is not positioned at the reference position B1, thespatial position of the marker unit 1110 is calculated by comparing theposition C2 and the size A2 of the enlarged image formed on the imageforming unit 1120 with the reference position C1 and the reference sizeA1 of the image of the pattern portion 1111 which is pre-stored in theprocessor 1130.

Meanwhile, as shown in FIG. 37d , when the distance D2 between themarker unit 1110 and the image forming unit 1120 is identical to thereference distance D1, the marker unit 1110 is positioned at thereference position B1 and the direction of the maker unit 1110 ischanged as θ, the calculated size A2 and position C2 of the enlargedimage of the pattern portion 1111 formed on the image forming unit 1120are identical to the reference position C1 and the reference size A1 ofthe image of the pattern portion 111 which is pre-stored in theprocessor 1310. Therefore, the direction of the marker unit 1111 iscalculated by calculating the rotated angle of the marker unit 1111 bycomparing the position for each pattern portion 1111 and the size changeof the pattern portion 1111 of the enlarged image I₁ of the patternportion 1111 with the reference position for each pattern portion 1111and the reference size of the pattern portion 1111 of the image I₂ ofthe pattern portion 111 which are pre-stored in the processor 1130.

As described above, an optical tracking system according to anembodiment of the present invention emits a parallel light of a patternportion 1111 from a marker unit 1110, forms an enlarged image of thepattern portion 1111 on an image forming unit 1120, and calculates aspatial position of the marker unit 1110 using the enlarged image of thepattern portion 1111. In other words, the spatial position and thedirection of a target to be calculated are calculated without reducingaccuracy by enlarging an image of the pattern portion 1111 and formingthe image on the image forming unit 1120, and therefore, an accuracy ofthe position of the marker unit is not dependent to a resolving power.

Therefore, an optical tracking system and a method using the sameaccording to an embodiment of the present invention has an effect ofexpanding an available area by detecting an exact spatial position and adirection of a target regardless of a distance of the target to becalculated, as well as, a system downsizing is also capable comparedwith conventional system by reducing size of a marker unit 1110.

Meanwhile, the present invention has advantage of tracking moreprecisely a spatial position and a direction of a target since an angleof view and a resolution of an enlarged image of an pattern portion 1111formed on the image forming unit 1120 are adjusted by adjusting a lightquantity of a light which is emitted from a light source 1140 andincident on a mirror portion 1113 of a marker unit 1110.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. An optical tracking system comprising: at least one marker configuredto be attached to a target, the at least one marker including therein:at least one pattern portion formed by a plurality of patterns andarranged to receive light irradiated by at least one external lightsource, the received light passing the at least one pattern portion orbeing reflected by the at least one pattern portion; and a first lensarranged to receive the light, which has passed the at least one patternportion or has been reflected by the at least one pattern portion, andconfigured to release a plurality of portions of the light, eachreleased portion of the light having passed a specific point of the atleast one pattern portion; at least one camera including: a second lensconfigured to receive and focus the light released from the first lens;and an image sensor configured to form an image of the at least onepattern portion based on the focused light; and a processor configuredto calculate a spatial position and a direction of the at least onemarker by using the image of the at least one pattern portion.
 2. Theoptical tracking system of claim 1, wherein the processor is configuredto: calculate the spatial position of the at least one marker by usingcoordinate information of the image of the at least one pattern portion,and calculate the direction of the at least one marker by using and thecoordinate information of the image of the at least one pattern portionand coordinate information of the spatial position of the at least onemarker.
 3. The optical tracking system of claim 1, wherein the processoris configured to: calculate the spatial position of the at least onemarker by using a position change or a size change of the image of theat least one pattern portion, and calculate the direction of the atleast one marker by using a position change or a size change of the atleast one pattern portion for each area of the image of the at least onepattern portion.
 4. The optical tracking system of claim 1, wherein thefirst lens comprises a fish-eye lens.
 5. The optical tracking system ofclaim 1, wherein the at least one marker further comprises a prismarranged to receive the light released from the first lens andconfigured to release the light to have a different angle of view.
 6. Atracking method comprising: by at least one pattern portion included inat least one marker of an optical tracking system, receiving lightirradiated by at least one external light source, the at least onepattern portion formed by a plurality of patterns and arranged toreceive the light irradiated by the at least one external light source,the received light passing the at least one pattern portion or beingreflected by the at least one pattern portion; by a first lens includedin the at least one marker, the first lens arranged to receive thelight, which has passed the at least one pattern portion or has beenreflected by the at least one pattern portion, releasing a plurality ofportions of the light, each released portion of the light having passeda specific point of the at least one pattern portion; by a second lensincluded in at least one camera of the optical tracking system,receiving and focusing the light released from the first lens; by animage sensor included in the at least one camera, forming an image ofthe at least one pattern portion based on the focused light; and by aprocessor of the optical tracking system, calculating a spatial positionand a direction of the at least one marker by using the image of the atleast one pattern portion.
 7. The tracking method of claim 6, whereincalculating the spatial position and the direction of the at least onemarker comprises: calculating the spatial position of the at least onemarker by using coordinate information of the image of the at least onepattern portion; and calculating the direction of the at least onemarker by using and the coordinate information of the image of the atleast one pattern portion and coordinate information of the spatialposition of the at least one marker.
 8. The tracking method of claim 7,wherein calculating the direction of the at least one marker comprises:calculating the spatial position of the at least one marker by using aposition change or a size change of the image of the at least onepattern portion; and calculating the direction of the at least onemarker by using a position change or a size change of the at least onepattern portion for each area of the image of the at least one patternportion
 9. The tracking method of claim 6, wherein the first lenscomprises a fish-eye lens.
 10. The tracking method of claim 6, whereinthe at least one marker further comprises a prism arranged to receivethe light released from the first lens and configured to release thelight to have a different angle of view.